From Landing Page to Creative

Most small advertisers have exactly one designed artifact: their landing page. Promovolve treats it as the source of truth for the ad — the campaign input is a URL, not a zip of banner assets.

The pipeline

1. Extraction. A Playwright browser (the LPWorker pool, running on cluster nodes with the crawler role) loads the landing page and extracts its raw material: headline candidates, body copy, images, and a brand kit — dominant background color, text color, and a palette of up to six swatches ordered by how much painted area each covers. The brand kit is measured from the rendered DOM, not guessed by a model, so the ad inherits the landing page’s actual look.

2. Rewriting. An LLM turns the extracted copy into the three-page magazine narrative — cover hook, story, call to action — under hard constraints: claims must be grounded in the landing page’s own text, and verbatim-sensitive details (prices, phone numbers) are carried through unchanged rather than paraphrased.

3. Rendering and verification. The creative is rendered headlessly and uploaded to object storage (Cloudflare R2, served through the CDN). An LLM then verifies it against two questions: does the ad actually match its declared content categories, and is it brand-safe — no adult, violent, or hateful content? The check reads the authored text where it exists and falls back to the rendered image only when it doesn’t; the verdict updates the creative’s verification and safety status and auto-derives its target categories.

Color is code, not model output

Text colors are never chosen by the LLM. A deterministic pipeline picks them: luminance decides a dark-on-light or light-on-dark palette, every combination is checked against the WCAG AA contrast ratio (4.5:1), and any brand-kit color that fails contrast is replaced by a compliant fallback. The prompt hard-codes the allowed hex values so the model cannot invent an unreadable one. If a creative looks wrong, the bug is in the contrast pipeline — a place you can set a breakpoint — not in a model’s mood.

The designer

Advertisers can hand-tune the generated creative in an in-browser designer. Its editing model took several iterations to get honest, and the invariants are worth stating because they define what a “creative” is:

• One image per page, defined by the expanded view. The image shown on page one of the full-screen spread is the page’s image everywhere — the folded cover and every slot size derive from it. There is no per-size image pinning; replacing the image in the expanded view replaces it everywhere, always.
• Text and color sync across sizes by default. Each text field carries a per-size “synced across all sizes” setting. Unsynced, edits stay local to that slot size; re-ticking sync adopts the current text as the shared value. Headline, body, and page-background colors additionally sync across the three pages, each with its own toggle (page background defaults to synced).
• Deletion is one-sourced. Deleting a field from the expanded view removes it from every size that carries it — and the confirmation dialog counts exactly which sizes those are, rather than claiming “everywhere.”

The folded and expanded views are two projections of one layout document, so nothing the advertiser does can make the cover advertise a different product than the magazine inside it.